Oropharyngeal candidiasis is the most common opportunistic infection in patients with AIDS. It can be treated with fluconazole, but resistance may develop. If so, treatment with Amphotericin-B is the norm, with well documented side effects. This is a multicenter double blind randomized comparative dose response study to evaluate the safety, tolerability and efficacy of MK-0991 as compared to Amphotericin B in the treatment of candidiasis. The drug has demonstrated potent antifungal activity in previous studies. Patients with fluconazole-resistance and fluconazole-sensitive candidiasis will be studied.